Hydraulic displacement amplifiers for fuel injectors

ABSTRACT

The present technology is generally related to hydraulic displacement amplifiers in fuel injectors. In some embodiments, a gaseous fuel injector includes a piezoelectric actuator, a working volume reservoir adjustable between a first volume and a second volume smaller than the first volume, and a combustion chamber valve in communication with the working volume reservoir and movable between a closed configuration when the working volume reservoir comprises the first volume and an open configuration when the working volume reservoir comprises the second volume. The gaseous fuel injector further includes a hydraulic displacement amplifier in operable connection with the actuator. The hydraulic displacement amplifier can have a plurality of pistons in communication with the working volume reservoir and configured to adjust the working volume reservoir from the first volume to the second volume.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/725,446, filed Nov. 12, 2012, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure is generally related to hydraulic displacement amplifiers for use in fuel injectors. Particular embodiments are directed to hydraulic displacement amplifiers for use in direct injection of gaseous fuels into internal combustion engines of multiple cylinders, sizes and compression ratios.

BACKGROUND

Fuel injection systems are typically used to inject a fuel spray into an inlet manifold or a combustion chamber of an engine. Fuel injection systems have become the primary fuel delivery system used in automotive engines, having almost completely replaced carburetors since the late 1980s. Fuel injectors used in these fuel injection systems are generally capable of two basic functions. First, they deliver a metered amount of fuel for each inlet stroke of the engine so that a suitable air-fuel ratio can be maintained for the fuel combustion. Second, they disperse the fuel to improve the efficiency of the combustion process. Conventional fuel injection systems are typically connected to a pressurized fuel supply, and the fuel can be metered into the combustion chamber by varying the time for which the injectors are open. The fuel can also be dispersed into the combustion chamber by forcing the fuel through a small orifice in the injectors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional side view of an injector configured in accordance with embodiments of the technology.

FIG. 2A is a cross-sectional side view of a hydraulic displacement amplifier configured in accordance with embodiments of the technology.

FIG. 2B is a magnified view of an amplification region of the hydraulic displacement amplifier of FIG. 2A in accordance with embodiments of the technology.

DETAILED DESCRIPTION

The present technology is generally related to hydraulic displacement amplifiers in fuel injectors. Particular embodiments are directed to hydraulic displacement amplifiers for use in the direct injection of gaseous fuels into internal combustion engines of multiple cylinders, sizes and compression ratios. In some embodiments, a gaseous fuel injector includes a piezoelectric actuator, a working volume reservoir adjustable between a first volume and a second volume smaller than the first volume, and a combustion chamber valve in communication with the working volume reservoir and movable between a closed configuration when the working volume reservoir comprises the first volume and an open configuration when the working volume reservoir comprises the second volume. The gaseous fuel injector further includes a hydraulic displacement amplifier in operable connection with the actuator. The hydraulic displacement amplifier can have a plurality of pistons in communication with the working volume reservoir that are configured to adjust the working volume reservoir from the first volume to the second volume.

Specific details of several embodiments of the technology are described below with reference to FIGS. 1-2B. Other details describing well-known structures and systems often associated with amplifiers, fuel injection systems, and ignition systems have not been set forth in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments of the technology. Many of the details, dimensions, angles, and other features shown in the Figures are merely illustrative of particular embodiments of the technology. Accordingly, other embodiments can have other details, dimensions, angles, and features without departing from the spirit or scope of the present technology. A person of ordinary skill in the art, therefore, will accordingly understand that the technology may have other embodiments with additional elements, or the technology may have other embodiments without several of the features shown and described below with reference to FIGS. 1-2B.

FIG. 1 is a schematic cross-sectional side view of an injector 101 configured in accordance with embodiments of the technology. The injector 101 is configured to inject fuel into a combustion chamber 105 and utilize a hydraulic displacement amplifier 150 to increase the pressure of gaseous fuel entering the combustion chamber. In further embodiments, the fuel is a liquid, a gaseous/liquid combination, a partial solid or slurry, or other material. The hydraulic displacement amplifier 150 is schematically illustrated in FIG. 1 and can be positioned at any location on the injector 101 and coupled to any of the features described in detail below. Moreover, in certain embodiments the hydraulic displacement amplifier 150 can be integral with one or more of the valve actuating components described in detail below. Furthermore, although several of the additional features of the illustrated injector 101 described below are shown schematically for purposes of illustration, several of these schematically-illustrated features are described in detail below with reference to various features of embodiments of the disclosure. Accordingly, the relative location, position, size, orientation, etc., of the schematically-illustrated components of the Figures are not intended to limit the present disclosure.

In the illustrated embodiment, the injector 101 includes a casing or body 113 having a middle portion 117 extending between a base portion 115 and a nozzle portion 119. The nozzle portion 119 extends at least partially through a port in an engine head 107 to position the nozzle portion 119 at the interface with the combustion chamber 105. The injector 101 further includes a fuel passage or channel 141 extending through the body 113 from the base portion 115 to the nozzle portion 119. The channel 141 is configured to allow fuel to flow through the body 113. The channel 141 is also configured to allow other components, such as a valve operator assembly 131, an actuator 123, instrumentation components, and/or energy source components of the injector 101 to pass through the body 113. According to additional features of the illustrated embodiment, the nozzle portion 119 can include one or more ignition features for generating an ignition event for igniting the fuel in the combustion chamber 105. For example, the injector 101 can include any of the ignition features disclosed in U.S. patent application Ser. No. 12/841,170 entitled “INTEGRATED FUEL INJECTORS AND IGNITERS AND ASSOCIATED METHODS OF USE AND MANUFACTURE,” filed Jul. 21, 2010, which is incorporated herein by reference in its entirety.

In certain embodiments, the actuator 123 can be a cable, stiffened cable, or rod that has a first end portion that is operatively coupled to a flow control device or valve 121 carried by the nozzle portion 119. The actuator 123 can be integral with the valve 121 or a separate component from to the valve 121. As such, the flow valve 121 is positioned proximate to the interface with the combustion chamber 105. Although not shown in FIG. 1, in certain embodiments the injector 101 can include more than one flow valve, as well as one or more check valves positioned proximate to the combustion chamber 105, as well as at other locations on the body 113. For example, the injector 101 can include any of the valves and associated valve actuation assemblies as disclosed in the patent applications incorporated by reference above.

The position of the flow valve 121 can be controlled by the valve operator assembly 131. For example, the valve operator assembly 131 can include a plunger or driver 125 that is operatively coupled to the actuator 123. The driver 125 can be a prime mover such as a piezoelectric, magnetostrictive, electromagnetic, electromechanical, pneumatic, or hydraulic force generator. The actuator 123 and/or driver 125 can further be coupled to a processor or controller 129. As explained in detail below with reference to various embodiments of the disclosure, the driver 125 and/or actuator 123 can respond to the controller 129. The controller 129 can be positioned on the injector 101 or remotely located away from the injector 101. The controller 129 and/or the driver 125 are configured to rapidly and precisely actuate the actuator 123 to inject fuel into the combustion chamber 105 by moving the flow valve 121 via the actuator 123. For example, in certain embodiments, the flow valve 121 can move outwardly (e.g., toward the combustion chamber 105) and, in other embodiments, inwardly (e.g., away from the combustion chamber 105) to meter and control the injection of the fuel. Moreover, the driver 125 can tension the actuator 123 to retain the flow valve 121 in a closed or seated position, and the driver 125 can relax or relieve the tension in the actuator 123 to allow the flow valve 121 to inject fuel. In other embodiments, the flow valve 121 may be opened and closed depending on the pressure of the fuel in the body 113 without the use of an actuator cable or rod. Additionally, although only a single flow valve 121 is shown at the interface of the combustion chamber 105, in other embodiments the flow valve 121 can be positioned at other locations on the injector 101 and can be actuated in combination with one or more other flow valves or check valves.

The injector 101 can further include a sensor and/or transmitting component 127 for detecting and relaying combustion chamber properties such as temperatures and pressure, and providing feedback to the controller 129. The sensor 127 can be integral to the valve 121, the actuator 127, and/or the nozzle portion 119 or a separate component that is carried by any of these portions of the injector 101. In one embodiment, the actuator 123 can be formed from fiber optic cables or insulated transducers integrated within a rod or cable, or can include other sensors to detect and communicate combustion chamber data. Although not shown in FIG. 1, in other embodiments, the injector 101 can include other sensors or monitoring instrumentation located at various positions on the injector 101. For example, the body 113 can include optical fibers integrated into the material of the body 113. In addition, the flow valve 121 can be configured to sense or carry sensors to transmit combustion data to one or more controllers 129 that are associated with the injector 101. This data can be transmitted via wireless, wired, optical or other transmission mediums to the controller 129 or other components. Such feedback enables extremely rapid and adaptive adjustments for desired fuel injection factors and characteristics including, for example, fuel delivery pressure, fuel injection initiation timing, fuel injection durations for production of multiple layered or stratified charges, combustion chamber pressure and/or temperature, the timing of one, multiple or continuous plasma ignitions or capacitive discharges, etc. For example, the sensor 127 can provide feedback to the controller 129 as to whether the measurable conditions within the combustion chamber 105, such as temperature or pressure, fall within ranges that have been predetermined to provide desired combustion efficiency. Based on this feedback, the controller 129 in turn can direct the hydraulic displacement amplifier 150 to manipulate the frequency and/or degree of flow valve 121 actuation.

The hydraulic displacement amplifier 150 can take on numerous forms according to different embodiments of the disclosure and can transfer or modify (i.e., amplify) the motion of the driver 125, the actuator 123, the flow valve 121, and/or to other components of the fuel injector 101. In another embodiment, the hydraulic displacement amplifier 150 transfers motion directly to the actuator 123 by any of the means described above. The actuator 123 in turn opens the flow valve 121 in a stroke responsive to the motion transfer, thereby altering the fuel distribution rate and/or pressure. In some embodiments, the hydraulic displacement amplifier 150 transfers motion to the flow valve 121 directly.

FIG. 2A is a cross-sectional side view of a hydraulic displacement amplifier 250 configured in accordance with embodiments of the technology. FIG. 2B is a magnified view of an amplification region 290 of the hydraulic displacement amplifier 250 of FIG. 2A. Referring to FIGS. 2A and 2B together, the hydraulic displacement amplifier 250 can include an anvil 264, an upper piston 265, and a lower piston 266 in hydraulic communication with the upper piston 265. The pistons 265, 266 can be movable to affect a first working volume 275 a and a second working volume 275 b (collectively, a “working volume 275”) in the hydraulic displacement amplifier 250. The working volume 275 can communicate with reservoir volumes of hydraulic fluid 276, 277, 278 a, 278 b (collectively, “reservoir volume”) by means of a check valve 272 and diametric leakage gaps 280 a, 280 b (collectively, “diametric gaps 280”) around the upper piston 265 and lower piston 266, respectively. In still further alternative embodiments, the diametric gaps 280 can be eliminated by adding active sealing, such as o-ring grooves, or vulcanized sealing systems. An orifice may then be included that precisely controls the flow rate into the appropriate reservoir volume from the working volume 275. In further embodiments, the piston arrangement may be altered such that instead of unidirectional motion amplification, the motion is amplified and reversed. In some embodiments, an orifice can be controllably varied by a suitable component such as a piezoelectric element.

In various embodiments, the check valve 272 can take on alternate forms, such as a ball valve, flapper valve, pintle valve, or spool type valve. Alternatively, the reservoir volume can be sealed by alternative means, such as with diaphragms, bellows, o-rings, or vulcanized sealing systems. In various embodiments, the filling of hydraulic fluid into the device may be accomplished by means of vacuum filling, high temperature baking, vibratory shaking, or other viable means to achieve a fluid-filled device with minimized air volume allowed. In some embodiments, the hydraulic displacement amplifier 250 can be sub-assembled in a self-contained state by adding retaining rings 273 a, 273 b, and a shell 268.

In operation, the hydraulic displacement amplifier 250 can transfer and/or amplify motion from a valve actuator (e.g., the actuator 123 shown in FIG. 1) to an injector valve (e.g., to a valve pin on the flow valve 121 shown in FIG. 1). For efficient direct injection of gaseous fuels, a fast-acting actuator such as a piezoelectric multilayer motion generator may be used. The actuator can initiate an initial displacement 261 that creates a displacement of the anvil 264 and the upper piston 265; the displacement momentarily reduces the working volume 275, thus increasing the pressure within the working volume 275. This pressure can increase until a static force 284 from the injector valve pin is overcome. The pressure created will also exert an increased force 262 back to the upper piston 265 and thus the actuator (not shown). At this point, the lower piston 266 is displaced by a distance 263 and the working volume 275 is restored.

The hydraulic displacement amplifier 250 can amplify motion between the valve actuator to the injector valve according to an amplification ratio. The amplification ratio R is, ideally, the ratio of the upper piston 265 hydraulic area A₁ divided by the lower piston 266 hydraulic area A₂, or R=A₁/A₂, where a hydraulic area A is the cross-sectional area of each piston in this arrangement. The ideal ratio R, however, assumes that there is no hydraulic fluid bulk modulus effects, volumetric influences, or leakages around the pistons 265, 266 or other leak points. The working volume 275, fluid bulk modulus, piston diameters, and diametric gaps 280 can be carefully chosen to achieve the desired amplification ratio.

The hydraulic displacement amplifier 250 can further serve to reduce operational constraints on the fuel injector. In various embodiments, the hydraulic displacement amplifier 250 can absorb effects due to thermal growth, thermal shrinkage, part geometry changes due to loads, gravitational effects, and other conditions that would limit the working parameters or actuator functionality of the injector. For example, in some embodiments both the upper piston 265 and the lower piston 266 are preloaded with a first spring 269 and a second spring 270, respectively, such that the working volume 275 is maintained without the influence of gravity or other effects. Alternatively, the first and second springs 269, 270 may be helical compression springs, wave springs, belleville washers, machined springs, urethane bushings, one or more magnets, or other suitable devices. In some embodiments, the hydraulic displacement amplifier 250 further includes at least one of a magnet, pneumatic cylinder, or spring coupled to at least one of the plurality of pistons and configured to return the hydraulic displacement amplifier to a starting position at the end of a hydraulic displacement amplification cycle.

In further embodiments, thermal effects can be mitigated by the check valve 272, which can permit one-way flow of hydraulic fluid from the reservoir volume of hydraulic fluid to the working volume 275 when a pressure differential is created due to thermal effects, changes to geometry, or other effects and conditions that the injector valve system may experience in operation. When pressure is created in the working volume 275, the pressure will exert a force on the check valve 272 and force it against a valve seat 271. This will cause leakage through the diametric gaps 280 around the pistons 265, 266 that will slowly reduce the pressure in the working volume 275 to normal conditions. In some embodiments, the reservoir volume is sufficiently larger than the working volume 275 in order to absorb leakage volumes of hydraulic fluid from the working volume 275. It can be appreciated that other means of containing reservoir volumes can be accomplished by means of diaphragms, o-ring seals 274, bellows, etc. In certain applications, the hydraulic fluid can be the same or a refined version of the liquid fuel that is suitable for the host engine. For example, in some embodiments, hydraulic fluids such as diesel or jet fuel, gasoline, and/or various fuel alcohols can be used. In some embodiments, the reservoir volume can extend around the actuator (not shown) and provide a means of hydraulic damping to the actuator assembly.

The hydraulic displacement amplifier 250 can offer several advantages over traditional systems. In some embodiments, the hydraulic displacement amplifier 250 can be used as part of an injector for a dedicated natural gas or gaseous fueling system for the automotive, heavy duty, or off road markets. For example, the hydraulically-pressurized gas can reduce injection time. This can be useful for a diesel engine (compression ignition) type of application, where the direct injection of a gaseous fuel traditionally takes too long or the injector cannot deliver enough gaseous fuel due to the low density characteristics of gaseous fuels. In other cases, the fuel system need not be a dedicated natural gas system, as diesel fuel can be used as a supplement and catalyst for combustion. In some applications, diesel fuel, gasoline, or other liquid fuel serves as an expendable amplifier working fluid and leakage can be added to the injected fuel. In such instances, replenishing supplies of such fuel working fluids can be added cyclically or occasionally to one or more of the reservoirs as previously described and/or to larger versions of such reservoirs.

Because of the low density characteristics of gaseous fuel, traditional systems require a very large valve arrangement and/or a high injector valve lift to sufficiently inject the required quantity of fuel in the amount of time needed for compliant emissions, burn characteristics, heat release, and power needs. In the case of a multilayer piezoelectric stack assembly, the force exerted is very high and can overcome a larger valve sealing arrangement, but is limited on available displacement. The present technology overcomes the displacement limitations of a piezoelectric multilayer actuator by amplifying the motion to the valve arrangement such that the injector has the ability to inject the required quantity of fuel in the amount of time allowable.

U.S. patent application entitled “MECHANICAL MOTION AMPLIFICATION FOR NEW THERMODYNAMIC CYCLES,” Attorney Docket No. 69545-8333.US01, and filed on or before Mar. 15, 2013, and U.S. patent application entitled “SYSTEMS AND METHODS FOR PROVIDING MOTION AMPLIFICATION AND COMPENSATION BY FLUID DISPLACEMENT,” Attorney Docket No. 69545-8336.US01, and filed on or before Mar. 15, 2013, are incorporated by reference herein in their entireties.

From the foregoing it will be appreciated that, although specific embodiments of the technology have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the technology. Further, certain aspects of the new technology described in the context of particular embodiments may be combined or eliminated in other embodiments. Moreover, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein. Thus, the disclosure is not limited except as by the appended claims. 

I/We claim:
 1. A gaseous fuel injector, comprising: a piezoelectric actuator; a working volume reservoir adjustable between a first volume and a second volume smaller than the first volume; a combustion chamber valve in communication with the working volume reservoir and movable between a closed configuration when the working volume reservoir comprises the first volume and an open configuration when the working volume reservoir comprises the second volume; and a hydraulic displacement amplifier in operable connection with the actuator, the hydraulic displacement amplifier having a plurality of pistons in communication with the working volume reservoir and configured to adjust the working volume reservoir from the first volume to the second volume.
 2. The fuel injector according to claim 1 wherein the plurality of pistons includes a first piston and a second piston, and wherein the first piston has a different cross-sectional area than the second piston.
 3. The fuel injector according to claim 1, wherein the hydraulic displacement amplifier further includes a check valve in communication with the working volume reservoir, and further wherein the check valve is responsive to a pressure condition in the hydraulic displacement amplifier.
 4. The fuel injector according to claim 1 wherein the fuel injector comprises a fuel injector in a diesel engine.
 5. The fuel injector according to claim 1 wherein the hydraulic displacement amplifier further includes at least one of a spring, magnet, or pneumatic cylinder coupled to at least one of the plurality of pistons and configured to return the hydraulic displacement amplifier to a starting position at the end of a hydraulic displacement amplification cycle.
 6. An injector for introducing fuel into a combustion chamber, the injector comprising: an injector body including— a base portion configured to receive fuel into the body; and a valve coupled to the body, wherein the valve is movable to an open position to introduce fuel into the combustion chamber; and a valve operator assembly, the valve operator assembly including— a valve actuator coupled to the valve and movable from a first position to a second position upon receipt of an initial motion; and a hydraulic displacement amplifier configured to receive the initial motion from the valve actuator, amplify the initial motion, and transfer the amplified motion to the valve.
 7. The injector of claim 6, further comprising a prime mover coupled to the valve actuator and configured to supply the initial motion to the valve actuator.
 8. The injector of claim 7 wherein the prime mover comprises at least one of a piezoelectric, magnetostrictive, electromagnetic, electromechanical, pneumatic, or hydraulic force generator.
 9. The injector of claim 6 wherein the hydraulic displacement amplifier comprises a plurality of operably connected pistons, wherein a first piston has a different cross-sectional area than a second piston.
 10. The injector of claim 6 wherein the injector comprises a fuel injector in a diesel engine.
 11. The injector of claim 6 wherein the injector comprises a combined fuel-injector and fuel igniter.
 12. The injector of claim 6 wherein the hydraulic displacement amplifier is automatically adjustable in response to at least one of a pressure or temperature condition.
 13. The injector of claim 6 wherein the hydraulic displacement amplifier further includes a check valve responsive to a pressure condition in the hydraulic displacement amplifier.
 14. A method of operating a fuel injector to inject fuel into a combustion chamber, the method comprising: introducing fuel into a body portion of the fuel injector, the body portion including a hydraulic displacement amplifier and a valve adjacent to the combustion chamber, the valve being moveable between an open position and a closed position; imparting a motion to the hydraulic displacement amplifier; hydraulically amplifying a magnitude of the motion; actuating the valve to move between the closed position and the open position; and introducing the fuel through the valve from the body portion into the combustion chamber.
 15. The method of claim 14 wherein imparting the motion to the hydraulic displacement amplifier comprises imparting the motion via one or more of a piezoelectric, magnetostrictive, electromagnetic, electromechanical, pneumatic, or hydraulic force generator.
 16. The method of claim 14 wherein hydraulically amplifying the magnitude of the motion comprises modifying the motion with a plurality of operably connected pistons.
 17. The method of claim 16 further comprising restoring the plurality of operably connected pistons to a starting position upon actuating the valve.
 18. The method of claim 14 wherein introducing the fuel into the combustion chamber comprises introducing the fuel into a diesel engine combustion chamber.
 19. The method of claim 14 wherein actuating the valve comprises automatically actuating the valve in response to a thermal or pressure condition in the body portion.
 20. The method of claim 14 wherein hydraulically amplifying the magnitude of the motion comprises reducing a working volume in the hydraulic displacement amplifier. 